(1) Field of the Invention
The present invention relates to a touch panel and a film body.
(2) Description of Related Art
Touch panels have been heretofore placed on display devices in, for example, game machines, portable information terminals, mobile phones, ticket-vending machines, conference tables, bank ATMs, personal computers, electronic notebooks, PDA, and so on, and widely used for performing operations of game machines and portable information terminals etc. Various studies have been heretofore conducted on the configuration of the touch panel, and for example, an electrostatic capacitance type touch panel, a resistance film type touch panel and the like are known. The electrostatic capacitance type touch panel is configured such that a dielectric layer is interposed between a pair of transparent planar bodies each including a transparent conductor having a predetermined pattern shape, and when a finger or the like touches an operation screen, a touch position is detected by utilizing a change in electrostatic capacity due to connection to the ground through a human body (for example FIG. 1 and FIG. 5 in Japanese Patent Laid-Open No. 2003-173238). The resistance film type touch panel is configured such that a transparent conductive film (resistance film) is provided on each of upper and lower transparent substrates, the transparent conductive films are made to face each other with an air layer held therebetween, and the transparent conductive films are brought into contact with each other by a pressing force to detect a touch position (FIG. 7 in Japanese Patent Laid-Open No. 2003-173238).
For example, as shown in the sectional view of FIG. 8, a touch panel 200 is mounted with a frame-shaped adhesive seal member 203, which is disposed on the outer edge portion of a display section 202 in a display device 201, interposed between the touch panel and the display section while an air gap (clearance) 204 is provided between a surface of the display section 202 and a back surface of the touch panel.
Here, surfaces of the touch panel 200 and the display section 201 have a slight distortion, and therefore when the touch panel 200 is placed on the display section 202 without providing the clearance 204, there exist a contact region where a back surface 200a of the touch panel 200 and a surface 202a of the display section 202 are in close contact with each other and a non-contact region where the back surface 200a and the surface 202a are not in close contact with each other. If the contact region is large enough to be visible, a boundary between the contact region and the non-contact region becomes conspicuous due to a difference between travel paths of light passing through the contact region and the non-contact region, so that an image or the like cannot be evenly displayed. For avoiding the above-mentioned situation, the touch panel 200 is mounted on the display section 202 with the clearance 204 provided between the surface of the display section 202 and the back surface of the touch panel 200.
However, concerning a touch panel placed with a clearance provided between the touch panel and a display section of a display device, there is the problem that it is difficult to maintain the clearance throughout the panel. Specifically, there is the possibility that the panel itself is warped or distorted as the touch panel is continuously used, or the touch panel is deformed at the time when the touch panel is pressed, and resultantly a part of the touch panel sticks to the surface of the display section, so that the back surface of the touch panel and the surface of the display section partially come into contact with each other as shown in FIG. 9. In a severe case, the touch panel persistently sticks on the surface of the display section, and it takes a long time until the original state is restored. In this case, there is the problem that due to a significant difference between travel paths of light in a region where the touch panel and the display section are in contact with each other (contact region) and a region where they are not in contact with each other (non-contact region), a boundary between the contact region and the non-contact region (hereinafter, referred to as a “water mark”) becomes conspicuous. If the water mark is generated, the contrast or color tone of an image or the like displayed by the display section may become uneven, thus making it impossible to evenly display the image or the like.
For avoiding contact of the touch panel with the display section, the thickness of an adhesive seal member may be set so that the clearance between the touch panel and the display section becomes relatively large, but in this case, there is the problem that thinning of an apparatus formed by the touch panel and the display device is restricted.
Thus, concerning a touch panel placed with a clearance provided between the touch panel and a display section of a display device, it is difficult to ensure both that a region where the touch panel and the display section are in contact with each other is hard to be conspicuous and that an apparatus formed by the touch panel and the display device is made thinner.